PRACTICAL TREATMENT — SCIENTIFIC TERMS. 
21 
NUMBER MORE IMPORTANT THAN SIZE. 
It is worthy of remark that by far the greater proportion of the 
damage caused by injurious insects is effected by species of very small 
size, whilst the large species are generally harmless. The two most 
serious fruit insects, the Codling-moth and the Plum-curculio, are both 
below the medium size, and the Apple bark-louse, the Apple-aphis, the 
Hessian-fly, and the Wheat-midge, are so minute that they woidd not 
be noticeable were it not for the wide destruction which they cause to 
some of our most valuable crops, in consequence of their excessive mul- 
tiplication. 
TREATMENT OF INJURIOUS INSECTS. 
For the details of treatment the reader is referred to the practical 
treatises and reports which have been published upon this subject. We 
can give here only an abstract of the methods to be pursued. 
First, hand-picking and destruction by machinery, as in the case of 
the Colorado potato-beetle ; second, poisoning by such substances as 
Paris-green, hellebore, and carbolic acid, as in the cases of the Potato- 
beetle, and the Currant saw-fly ; third, rendering their food distasteful 
and repugnant to them by the application of such substances as ashes, 
lime, and whale-oil soap, which are applicable to all foliage-eating in- 
sects ; fourth, anticipating their attacks by planting at such times as 
will cause the crops to sprout or to mature too early or too late for them, 
both of which plans are exemplified by winter wheat, in its relation to 
the Chinch-bug and the Hessian-fly ; and fifth, when all other means 
fail, preventing their ravages by abstaining for a year or two from rais- 
ing the damaged crops. To these may be added, in certain favorable 
instances, the transportation and colonization of friendly parasites. 
An experiment of this kind has been performed by the author by the 
transportation from the central to the northern parts of the State of 
Illinois, ot the minute Clialcis-fly, which is parasitic upon the Oyster- 
shell Park-louse. 
The above list exhibits the most common methods of contending with 
injurious insects, and these methods admit of almost indefinite modifi- 
cation. Put they can be most usefully described in connection with the 
particular species of insect to which they are respectively applicable. 
USE OF LEARNED AND SCIENTIFIC TERMS. 
With regard to the use of scientific terras, derived mostly from the 
Oreek and Latin languages, it is to be remarked that though they may 
appear difficult and forbidding, at first sight, the student soon becomes 
familiarized with them, and finds them to be almost indispensable by 
enabling him often to express in one or two words what would require a 
